Field of the Disclosure
The present disclosure relates generally to wireless communication systems and, more particularly, to wireless hotspots in wireless communication systems.
Description of the Related Art
The demand for mobile wireless data has been growing at an exponential rate and is expected to continue to grow by many orders of magnitude in the coming years. Meeting the increasing demand will require a corresponding increase in the amount of spectrum available for wireless communication. The available spectrum can be increased by combining licensed frequency bands with unlicensed frequency bands. Unlicensed frequency bands are portions of the radiofrequency spectrum that do not require a license for use and may therefore be used by any device to transmit or receive radio frequency signals. For example, the Unlicensed National Information Infrastructure (UNII) is formed of portions of the radio spectrum that include frequency bands in the range of 5.15 GHz to 5.825 GHz such as the U-NII-1 band in the range 5.15-5.25 GHz, the U-NII 2a, b, c bands in the range 5.25-5.725 GHz, and the U-NII 3 band in the range 5.725-5.825 GHz. Unlicensed frequency bands can be contrasted to licensed frequency bands that are licensed to a particular service provider and may only be used for wireless communication that is authorized by the service provider.
In order to take advantage of the bandwidth provided in the licensed spectrum and the unlicensed spectrum, user equipment can implement multiple radios for concurrent access to interfaces in the licensed frequency bands and the unlicensed frequency bands according to different radio access technologies. For example, user equipment may implement a radio to support an LTE interface in the licensed spectrum (LTE-L), a radio to support an LTE interface in the unlicensed spectrum (LTE-U), and a radio to support a Wi-Fi interface in the unlicensed spectrum. The different radios must be sufficiently isolated from each other to prevent collisions of transmitted or received signals. For example, a typical Wi-Fi transmit power of a smart phone is approximately 18 dBm and the in-band blocking requirement for LTE is −30 dBm, which implies that the Wi-Fi transmitter and the LTE receiver must be isolated from each other by at least 48 dBm. Frequency separation can provide sufficient isolation between the licensed frequency bands and the unlicensed frequency bands. However, there is no guarantee that signals transmitted by different nodes in the unlicensed frequency bands will be isolated from each other by frequency separation.